This invention relates to ultrasonic diagnostic imaging systems and, in particular, to ultrasonic diagnostic imaging systems which produce spatially compounded images that are adaptively processed.
U.S. Pat. No. 6,126,598 and the parent application Ser. No. 09/335,058 describe apparatus and methods for performing real time spatial compounding of ultrasonic diagnostic images. Spatial compounding is an imaging technique in which a number of ultrasound echoes of a given target that have been obtained from multiple look directions or angles are combined into a single compounded image by combining the data at each point in the compound image which has been received from each angle. The compounded image typically shows lower speckle and better specular reflector delineation than conventional ultrasound images from a single viewpoint. These particular patents describe spatial compounding systems that are adaptively variable to change the number of signals from different look directions that are combined as a function of imaging conditions. For example, when the motion of the scanhead is relatively high, the number of look directions used for a given compound image is reduced. When the scanhead is relatively stationary, the number of look directions is increased. In the parent patent application, the number of look directions is increased when imaging at shallow depths, and is decreased when imaging at greater depths.
These adaptive techniques are useful for improving the quality of real time spatially compounded images, as they prevent problems such as image blurring and undesirably low frame rates. It would be desirable to have other adaptive techniques which improve image quality for particular diagnostic applications and imaging targets. For example, a cardiologist looking for plaque buildup on blood vessel walls would want images optimized for discerning vascular structures, whereas an orthopedist looking for muscle and joint injuries would want images optimized for discerning muscle tissue and tendons. Accordingly it would be desirable to be able to optimize the image quality of spatially compounded images for the type of diagnosis being performed, and to be able to do so adaptively.
In accordance with the principles of the present invention, spatial compounding of ultrasonic echoes from different look directions is adaptively varied to vary the manner in which the echo data is combined. In one aspect, the combining process is automatically chosen in response to the selection of a particular diagnostic procedure by the clinician. In another aspect the combining process is dynamically variable in response to a characteristic of the received echo signals, enabling different areas of an image to be selectively combined by different processes. In one embodiment the selection of combining processes is a function of the variation in the echo data with look direction. In another embodiment the selection of combining processes is a function of control signals produced by an image processor. Control signals from an analysis of the echo data may further be used to highlight certain characteristics in the image rather than varying the combining techniques over the image.